main() {
  //数值类型
  num age = 18;
  print(age);
  //double类型
  double height = 19.99;
  height = 19;
  print(height);

  int age1 = 18;
  print(age1);

  String name = '张三';
  print(name);

  String name1 = '李四' + '123';
  print(name1);

  String name2 = '小红$name';
  print(name2);
  
}
